Apathy, common in neurological disorders, is defined as disinterest and loss of
motivation, with a reduction in self-initiated activity. Research in diseased
populations has shown that apathy is associated with variations in the volume of
brain regions such as the anterior cingulate and the frontal lobes. The goal of
this study was to determine the neural signatures of apathy in people with
penetrating traumatic brain injuries (pTBIs), as to our knowledge, these have not
been studied in this sample. We studied 176 male Vietnam War veterans with pTBIs
using voxel-based lesion-symptom mapping (VLSM) and apathy scores from the UCLA
Neuropsychiatric Inventory (NPI), a structured inventory of symptoms completed by
a caregiver. Our results revealed that increased apathy symptoms were associated
with brain damage in limbic and cortical areas of the left hemisphere including
the anterior cingulate, inferior, middle, and superior frontal regions, insula,
and supplementary motor area. Our results are consistent with the literature, and
extend them to people with focal pTBI. Apathy is a significant symptom since it
can reduce participation of the patient in family and other social interactions,
and diminish affective decision-making.